Telephone system.



PATENTED JULY 17, 1906.

W. W. DEAN.

TELEPHONE SYSTEM.

APPLIOATIONVIILED FEB. s. 1904.

\IIIJ.

UNITED STATJJSPATENT OFFICE.

WILLIAM DEAN, OF CHICAGO, ILLINOIS, ASSIGNOR TO KELLOGG SWITCHBOARD AND SUPPLY COMPANY, OF CHICAGO, ILLINOIS, A

CORPORATION OF ILLINOIS.

T ELEPHON E SYSTEM.

Specification of Letters Patent.

.Applloatlon flled'lebruary 8, 1904. Serial N 0. 192,418.

Patented July 17, 1906.

To allpwh omyit may conceriz: v

Be it known that I, WILLIAM W. DEAN, a citizenofthe United States of- America, and

-a resident of Chicago, county of Cook, and

State of. Illinois, have invented anew and useful Im rovement in Telephone Systems,

' of which t e following is a specification.

My invention relates to tele hone systems partaking. of the nature of bot the so-called intercommunicating systems and partyline systems; I

This invention is of particular advantage where a single line of considerable length is desired nd where such line must accommodate a number of stations scattered alongit at points perhaps several miles apart. Suchsmall towns.and at the same time to have, the a paratus at each of these stations of the 'sim est possible character, so that they are not ia-ble to get out of order and are capable of withstanding the rough usage of trainmen v and others unaccustomed to the frequent use of the tele hone; It is particularly desirous with such ines to lace the source or sources of energy required for the proper operation of the calling and talking instruments at some point along the line where some one is in attendance at all times and refe'rably where skilled attendants are availa le This may occur, of course, at some large cityor at some point where the railroad is maintaining an electric or other plant. By thus locating the sources of energy at such a point and placing at each of the stations on the line only the necessary mechanical apparatus for the various operations of talking and signaling a system is secured which is of particular advantage for the uses stated.

In carrying out my invention I preferably locate a source of steady current and a source ofringing-current at one pointand from said sources a pair of line-wires constituting a metallic line are extended throughout the re-' gion in which it is desired to locate the subscribers stations; At each-of the stations there is provided an ordinary talking set as j -well as the signaling-bell, together with a suitable calling button or switch which when depressed causes ringing-current from the said ringing-generator to traverse the various signaling-bells located upon the line, whereb with a suitable code of signals any subscri er is enabled to call the other subscribers upon the line. When the parties are in communication, the source of current at the central point furnishes the current for conversation to all the partiesupon the line. Thus each station on the line is provided with only the simplest apparatus, which is not liable to get out of or er and which will with stand rough usa 'e' and is capable of manipulation by unskil ed persons. If the stations on the telephone-line are located at isolated points, thetrainmen and any others intended to have access theretomay be provided with a key to unlock the box in which the set is placed. As many. lines as are desired may of course besupplied from said central source by varying the capacity thereof according to the number ,of lines supplied.

My invention is illustrated in'the accompanying drawing, in which the figure is a diagram of severalcf such party-lines, each provided with means for intercommunication.

In this diagram, L, L L and L indicate thelines, which are shown extending in two limbs 2 and 3 throughout their respective districts from the oint at which the source of steady current and the source of ringingcurrent G are located. These lines are connected with the battery-leads 4 and 5, connected respectively, with the live and grounded poles of the battery B. The ringmg-generator G is rovided with a common lead 6 to an plyeac of the lines with ringingcurrent, as hereinafter specified. At the central point in addition to the generators Band G there is also provided for each line a relay R, the windings 7 and 8 of which are included in the respectlve line conductors 2 and 3 and are difi'erentially wound with respect to currentsover the metallic line, said windings 7 and 8 being preferably placed end on upon the core of the relay or otherwise separated so that though differentially-wound sufficient impedance is presented to the .ra idly-varying voice-currents in the metallic ine to prevent them from being short-circuited through the battery B. This relay is provided with a pair of normally open contacts 9 and 10, the

latter being connected withithe line conductor 3, while'the' former is connected through the medium of a branch conductor 11 with' the ringing-generator lead 6.

12 and 13, which are normally closed and included in the line conductor 3.

Iliave shown only three's'tations A, D,

and F on each line but .it will be understood ,thatany desired number within reasonable limits may be added thereto. In the case of lines L and L I have shown a simple arrangementof substation apparatus,.transmitters 14 and receivers 15 beinglincluded in bridgesof the line conductors 2 and 3, which. bridges are normally open at the switch-hook 16. A signaling-bell 17 of ordinary type and a suitable condenser 18 are located in'a; sec- 'ond. bridge at each station.

The substation arrangement which I ,prefer to use, however,

is shown in connection'with the various stations upon the lines L and L, this arrangee ment including the call-bell 17 and/Icondenser 18. in a bridge of the line conductors that is normally closed by the switchhook 16, but-which is opened when the receiver 15 is lifted from the hook,- the said receiver ,-the

transmitter 14, condenser 18, and a suitable.

retardation-coil 19 being then suitably connected in the circuit for conversation. ,This

subscribers arrangement is shown more fully in my Patent No. 747,331, dated December 15, 1903. At each substation I place a pushbutton 20, electrically joined to the conductor 2 and which when depressed is adapted to make connection with a ground branch 21.

' The operation of my invention is as follows: Any subscriber desirin to converse with any other subscriber upon t e same line'depresses hiscallb'utton 20, which completes a circuit,

- from the live pole of the battery B over the common lead 4, the line conductor 2- of the ,calling-partys line, through windin 7 of'relay R of, that line, and thence over e conductor 2 to the substation at which-the'but- 'ton is'depressed, and through the call-button 20 and ground branch 21 .to pleting a path for'currentlrom the battery B, since the opposite terminal of said battery round, thus comis also grounded. The current in this path,

through the winding 7 of the relay R, en'ergizes said relay, which attracts its armature 9 and closes together its normally open con tacts 9 and'lO. The closin together of these contacts permits currento'm the ringinggenerator G to'flowv out 'over the common lead 6, the branch conductor 1 1 of thecallingline, contacts 9 and 10 of relay R, over line, conductor 3 of the telephone-line upon which the calling party islocated, thence through all the signaling-bell bridges at the various substations upon the line in multiple, and thence by Way of line conductor 2 and ringing-button 20 at the calling-station to ground.

7 In the case of lineslL and L I have shownthe said relays provided with an additional set of contacts -it is of course app The ringing-current being either alternating or pulsatin in character passes readily through the con ensers '18 in the bell-bridges and serves to operate the several bells 17, located upon that line? With a suitable code of sig nals, therefore, any subscriber or any one at anysubstation is enabled to .call any of the other substations.

up their receivers, they are in communication over the line upon which they are located and the battery B is furnishin current for the operation of their transmitters. The current from the battery B during conversation fioWs through the windin s7 and8' of' the relay R; but owing to the. 'iflerential arrange- -ment of these windings said relay remains inactive to the steady currents, so that the cbntaots 9 andlO remain open. At the same time, since the windings 7 and 8 are not superimposed or twin-wound or otherwise When the party called responds to thesignal and both parties take closely associated, the-rapidly-varying voicecurrents are not neutralized, and sufficient impedance results in said windings to confine the voicercurrents to the external portion. of

the telephone-line in use andpreventing them frombeing short-circuited throu h the batteries.- The windings 7 and 8 of t e re lays R are preferably of five hundred ohms resistance, and the battery B has a Volta e of about. fifty. The generator Gris preferab y.

a continuousy-operated power-generator. The electrical dimensions of the other parts may be those ,usually employed or, such as are suitableor desired. I

In the case of lines L and L it will be ob. served that when the relays R are operated bythe depression of a call-button at any of the stations the line conductor 3. is opened at the contacts 12 and 13 of said relay, whereby all tendency of the ringing-current to be confined locally at the power-station is prevented; but it;is' apparent that in the arrangement of as .well as their high ohmic. resistance, renders the same fully operative. The apparatus at the substations is of simple character and not liable to get out-of order by eitherrough or infregue'nt usage or in being operatedby unskille persons, and thereare no scattered sources of current to be inspected and maintained upon thel'ine. It is possible with this arrangement to locate stations at isolated sidings and other points along a railway-line without undue expense lines L and I the retardation of the coils 8,

on account of maintenance and which ,is capable of withstandingthe shocks, jars, andany general rouglihandling to which they would be subjected by the, men of the train crews.-

'- Although I have'inentioned specifically the most. advanta eous use of my invention, licable to other places and other relations.

Various changes and modifications may be made in the details of the invention without departing from the scope or principle of the invention I claim, and desire to secure by Letters Patent, is

1. In a telephone system, the combination with'a telephone-line, of a plurality of substations on said line, a source of current permanently connected therewith by a continuous conductor free from series contacts or possible .variable resistances, a differential relay having its coils interposed betweensaid source and the limbs of the telephone-line, a

single source of ringing-current for the line, a normally open contact of said relay adapted by its actuation to connect said source of ringing-current with one limb of said line, a normally open ground connection at each substation of said line adapted to be closed to send current through one side only of said relay, whereby the relay is actuated to place ringing-current upon the line to signal the desired station, substantially asdescribed.

2. In a telephone system, the combination with a telephone-line having a plurality of substations thereon, each bridged in a normally open circuit between the limbs of said line, a single source of current permanently connected with the line and adapted to fur- I nish current for the operation of the substal l r l tion-transmitters, a differential relay havin its coils interposed between said source and the limbs of said line, a single source of ring ingcurre nt for the line, a normally open coni tact of said difierential relay'adapted when closed to connect said source of ringing-current with one limb of said telephone-line, a

third conductor normally disconnected'from said telephone-line at the substations but permanently connected with one side of said directcurrent source, a key at each of said sab- Having thus descr bed my invention, what I stations for connecting one limb of the telephone-line with said third conductor whereby current is caused to flow through one coil only of said difi'erential relay to, actuate it, causing ringing-current to be placed upon the other limb of the line, substantially as described.

3. In a telephone system, the combination w-itha metallic telephone-line, of a plurality of substations normally bridged in open circuit between the limbs of said line, an annunciator at each of said substations, a common battery for said plurality of substations permanently connected to the limbs of said telephone-line through conductors free from se ries contacts or possible variable resistances, a differential relay having its coils interposed between said line and said source of current, a source of ringing-current for said line, a normally open contact for said differential relay adapted by its actuation to connect said souce of ringing-current with one limb of the telephone line, and means associated With each of said substations for actuating said differential relay, thereby connecting the ringing-current with the telephone-line to si nal any of the desired substations thereon, su bstantially as described.

Signed by me at Chicago, county of Cook, State of Illinois, this 31st day of December, 1903.

Witnesses:

E. A. GARLOCK, ROBERT TiEwIs AMns.

l/VILLL-XM XV. DEAN. 

